Q: In a particle accelerator, a proton has an acceleration of $$9.0 \times 10$$^{13}$$\ \mathrm{m/s^2$}. $$The mass of a proton is $$1.67 \times 10$$^{-27}$$\ \mathrm{kg}. $$What is the net force exerted on the proton?

$$1.5 \times 10$$^{-13}$$\ \mathrm{N}$$

Question 1

An astronaut is floating away from her spaceship in space with no tether. She is holding a large wrench. According to Newton's Third Law, what should she do to move back toward the spaceship?

Accepted Answer

Throw the wrench away from the spaceship.

Question 2

Two cars of equal mass collide head-on. Car A has an initial velocity of $$40\ \mathrm{m/s}$$, and car B has an initial velocity of $$-20\ \mathrm{m/s}. $$Which statement best describes the forces exerted by the cars on each other during the collision?

Accepted Answer

A exerts equal magnitude force on B as B exerts on A.

Question 3

A $$75\ \mathrm{kg}$$ box rests on a perfectly smooth horizontal surface. What is the minimum horizontal force needed to start the box moving?

Accepted Answer

Any nonzero horizontal force will start the box moving.

Question 4

A $$450\ \mathrm{kg}$$ sports car accelerates from rest to $$100\ \mathrm{km/h} in$$ $$4.80\ \mathrm{s}. $$What is the magnitude of the net force exerted on a $$68.0\ \mathrm{kg}$$ passenger during the acceleration?

Accepted Answer

$$394\ \mathrm{N}$$

Question 5

A woman is straining to lift a large crate but cannot lift it off the ground. Let $$P be $$the upward force she exerts, $$C$$ the vertical contact force from the floor, and $$W$$ the weight of the crate. Which equation correctly relates these forces?

Accepted Answer

$$P + C = W$$

Question 6

A ball is launched from the ground at an angle and follows a parabolic trajectory, passing through points $$P$$, $$Q$$, and $$R. $$Which diagram best represents the force(s) acting on the ball at these points, assuming negligible air resistance?

Accepted Answer

The diagram showing only a downward force at all three points (gravity only).

Question 7

An elevator car suspended by a vertical cable is moving downward but slowing down. The tension in the cable must be:

Accepted Answer

Greater than the force that Earth exerts on the elevator car.

Question 8

A $$45\ \mathrm{kg}$$ person stands on a scale in an elevator, and the scale reads a steady $$410\ \mathrm{N}. $$Which statement must be true?

Accepted Answer

The elevator is accelerating downward at a constant rate.

Question 9

A tow truck can accelerate at $$3.0\ \mathrm{m/s^2$} on $$its own. What will be its acceleration when towing a bus of twice its mass with a horizontal chain of negligible mass?

Accepted Answer

$$1.0\ \mathrm{m/s^2$}$$

Question 10

A $$10\ \mathrm{lb}$$ object is suspended from two spring scales in series, each of negligible mass. Which statement about the readings in the scales is true?

Accepted Answer

None of these is true.

Question 11

You push on box $$G$$ which is next to box $$H$$, causing both to slide along the floor. According to Newton's Third Law, what is the force paired to your push?

Accepted Answer

The force that box $$G$$ exerts on you.

Question 12

A large block of ice is on the floor of a train car moving at constant velocity. Suddenly, the train slams on its brakes and slows down. Which force diagram best represents the forces on the block of ice while the car is slowing down?

Accepted Answer

The diagram showing only vertical forces (gravity and normal force).

Question 13

A truck is towing a car whose mass is one quarter that of the truck. If the force exerted by the truck on the car is $$6000\ \mathrm{N}$$, what is the force exerted by the car on the truck?

Accepted Answer

$$6000\ \mathrm{N}$$

Question 14

A $$10\ \mathrm{kg}$$ object is hanging from a wire in an elevator that is traveling upward. The tension in the rope is measured to be $$75\ \mathrm{N}. $$What is the magnitude and direction of the acceleration of the elevator?

Accepted Answer

$$2.3\ \mathrm{m/s^2$}$$ downward

Question 15

In a particle accelerator, a proton has an acceleration of $$9.0 	imes 10$$^{13}$$\ \mathrm{m/s^2$}. $$The mass of a proton is $$1.67 	imes 10$$^{-27}$$\ \mathrm{kg}. $$What is the net force exerted on the proton?

Accepted Answer

$$1.5 	imes 10$$^{-13}$$\ \mathrm{N}$$

Question 16

A car and its passengers slow down with an acceleration of $$8.0\ \mathrm{m/s^2$}. $$What magnitude force does a $$50\ \mathrm{kg}$$ passenger exert on the seat belt in such a stop?

Accepted Answer

$$400\ \mathrm{N}$$

Question 17

Two carts of masses $$m_1 = 0.6$$\ \mathrm{kg}$$ and m_2$ = 1.2\ \mathrm{kg}$$ collide on a frictionless track. At $$t = 1.5\ \mathrm{s}$$, the force that Cart 2 exerts on Cart 1 is $$-1\ \mathrm{N}. $$What is the instantaneous acceleration of Cart 1 at this instant?

Accepted Answer

$$-1.67\ \mathrm{m/s^2$}$$

Question 18

Why might someone watching two carts collide not immediately realize that the carts exert equal-magnitude forces on each other during the collision?

Accepted Answer

Because the carts have different masses, so their accelerations are different even though the forces are equal.

AP Physics 1: Newtonian Mechanics – Forces, Motion, and Newton's Laws

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